学习笔记“Enterprise_Integration_Patterns_-_PLoP_Final_Draft_3.pdf”

1. Introduction

This paper introduces a set of integration patterns harveted from multiple years of hands-on
enterprise integration work with a variety of organizations.

Depending on their primary purpose, the patterns are grouped into:
message routing patterns,
message transformation patterns and
message management patterns.

2. The need for integration

Integration solutions present unique challenges due to their sheer size as well the number of
layers they span
- from high-level process management down to network packet routing and systems management.

3. Integration Strategies

Most commonly used techniques:
a. Batch Data Exchange
strengths: simple, physical decoupling, asychronize, persistence, language independent.
weakness: outdated-prone cause integrity problem, large amounts of unnecessary data transmisson.

b. Shared Database
strengths: resolve synchronization issues and the replication of hugh amounts of data.
weakness: difficulty of defining a data model fits all applications, performance bootleneck.

c. Raw Data Exchange
direct data exchange through network data transfer protocals, such as TCP/IP Sockets.
advantage: information can be propagated right as the data is modified in the source system.
challenge:
receiving system should be always available.
exchange data is of byte-by-byte, unstructured data stream.

d. Remote Procedure Call
advantage: be able to transparently invoke a function implemented in another application.
drawback:
unreliable,
synchronous communication,
point-to-point connections.
hard to interoperate between different vendor-provided products.

e. Messaging
Messaging systems try to overcome the drawbacks of the previous solutions by providing reliable,
asychronous data transfer.
An application can publish data to the integration layer and can be assured that the data will be
delivered to the recipient(s).
The originating system is not required to wait for an acknowledgement and can continue the
primary process flow. Messaging systems also incorporate addressing schemes that avoid the
difficult to maintain point-to-point connections that are typical in RPC systems

4. Message-Oriented Middleware

4.1 Pattern Categories

4.2 Pattern Description and Notation

4.3 Examples

5. Message Routing Patterns

5.1 Pipes and Filters

5.2 Content-Based Router

5.3 Example

5.4 Sequencer

5.5 Example

5.6 Aggregator

5.7 Distribution with Aggregate Response

5.8 Broadcast with Aggregate Response

5.9 Recipient List

5.10 Routing Table

6 Message Transformation Patterns

6.1 Data Enricher

6.2 Store in Library

6.3 Content Filter

7. Message Management Patterns

7.1 Control Bus

7.2 Message header

7.3 Envelope Wrapper / Unwrapper

7.4 Message History

7.5 Message Store

7.6 Test Message

8. Visual Pattern Language